Electric lighting apparatus



Feb.9, 1943. E. B. Moss ELECTRIC LIGHTING APPARATUS Filed Jan. '7, 1942Patented Feb. 9, 1943 UNITED STATES PATENT OFFICE ELECTRIC LIGHTINGAPPARATUS company Application January 7, 1942, Serial No. 425,944 InGreat Britain November 19, 1940 1 Claim.

This application corresponds to the application of S. Smith & Sons(Motor Accessories) Limited and Eric Beecroft Moss, Serial No.16,6'79/40, which was filed in Great Britain on November 19, 1940.

This invention relates to electric lighting apparatus employing electricdischarge lamps, the radiation from which may be varied by altering thevalue of the current. The invention is concerned with such apparatus ofthe kind employing a plurality of electric discharge lamps each having aseries impedance, the lamps with their impedances being connected inparallel to a supply source. If the applied voltage varies, it is foundthat unless the lamps are matched, one or other of them may beextinguished at lower voltages, while the remainder continue to radiate.The object of the invention is to overcome the difliculty of thisirregular operation.

According to this invention an electric lighting apparatus of the'kindspecified above is characterized in that means is provided forcompensating and equalizing the different voltage characteristics of thelamps and in that means are provided for simultaneously adjusting saidseries impedances. Thus, after the initial compensation of the voltagecharacteristics of the lamps the radiation of the lamps may besimultaneously adjusted by one control and without the disadvantage ofany lamp becoming prematurely extinguished when the applied voltageisreduced.

The compensating and equalizing means may comprise individuallyadjustable impedances connected respectively in series with saidsimultaneously adjustable impedances.

In the case where the apparatus is for use with a D. C. supply aninverter is provided for supplying the A. C. to the lamps, whichinverter and impedances are arranged to form a single unit.

In applying the invention for illuminating an instrument panel, forexample of an aircraft, there is provided in combination with anelectric lighting apparatus as referred to above, an instrument panelhaving the visible parts of its instruments treated with a materialwhich fluo resces under the action of ultra-violet ray, the lamps ofwhich apparatus are arranged to direct the rays on to the instrumentsand have associated therewith filtersto prevent the emanation of visiblelight.

The following is a'description of one embodiment of the invention,reference being made to the accompanying drawing, in which:

Figure 1 is a perspective diagrammatic view of an instrument panelincorporating a lighting 6 iii) , fiuoresces under the action of thoserays.

side of a group of instruments I2. Interposed between each lamp and thegroup of instruments is a screen I3 arranged to cut out visible rays butwhich pass ultra-violet rays. The instrument may be provided withsuitable windows it for the passage of the rays and the graduations i501 the instrument may be treated with a material wll gh e pointers ofthe instrument may also be similarly treated. The lamps are energized bya source of high-potential alternating current which may be provided bythe output side of a transformer it which steps up a source ofalternating supply provided by an inverter unit I! connected throughcables [8 with a source of direct supply. The inverter may be of thevibrator type.

As best seen in'Figure 2, one pole of each lamp is connected by a wireiii to one output terminal of the transformer l6, while the other outputterminal of the transformer is connected through a wire 20 and parallelcircuits 2| and 22 with the other pole of each lamp. The circuit 21contains a trimming resistance 23 and a light-adjusting resistance 24 ofan order ofv about 20,000 ohms. Similarly, the circuit 22 contains atrimming resistance 25 and a light-adjusting resistance 26. The twolight-adjusting resistances are ganged together as indicateddiagrammatically at 21, while the two trimming resistances areindividually adjustable. The inverter, transformer and the variousresistances are mounted together on the instrument panel to form a unit.If desired, this unit may'be separate from the instrument panel and isthen provided with two leads for at tachment to the lamps and two leadsfor connection with the source of D. C. supply.

In operation, after initial trimming to compensate for differences incharacteristics of the lamps the intensity of the illuminations may bevaried over a wide range by adjustment of the ganged variableresistances without risk of either lamp being extinguished.

I claim:

The combination with an instrument panel having its instruments treatedwith a material which fluoresces under the action of ultra-violet raysof a plurality of ultra-violet ray discharge lamps adapted to illuminatesaid instruments, filters associated with said lights and adapted toprevent emanation of visible light, a common source of current for saidlamps, manually ad- .iustable means for regulating the voltage appliedto each lamp for compensating and equalizing the different voltagecharacteristics of the discharge lamps, an adjustable impedance inseries with each lamp and means for simultaneously adjusting said seriesof impedances to simultaneously vary the light from each to the samedegree.

ERIC BEECROFI MOSS.

